In a head-to-head comparison of six OCT devices, the Spectralis spectral domain OCT (Heidelberg Engineering) showed the lowest co-efficient of variation in a test-retest study.
The study, conducted by Dr Ute Wolf-Schnurrbusch and colleagues from the University of Bern, compared central retinal thickness (CRT) measurements in healthy eyes using different commercially available OCT devices and then compared the intersession reproducibility of the measurements. The instruments used were: the Stratus OCT (Carl Zeiss Meditec), SOCT Copernicus (Reichert/Optopol Technology), Spectral OCT/SLO (Opko/OTI), RTVue-100 (Optovue Corporation), Spectralis HRA+OCT and Cirrus HD-OCT (Carl Zeiss Meditec).
The study found that CRT measurements differed significantly between the various devices, with the Spectralis and Cirrus HD-OCT demonstrating higher values than all other instruments. The Spectralis was the only device with a coefficient of variation below 1.0 and the only instrument with a Smallest Measurable Change of less than 2 microns.
“The high repeatability of the Spectralis HRA+OCT measurements is most likely related to the unique feature of the system that allows eye tracking during the scanning process and automatic recognition of the exact same scan location for follow-up examination,” commented Dr Wolf-Schnurrbusch in a Heidelberg press release. “By using this feature for all follow-up scans with the Spectralis HRA+OCT we could minimise extrinsic factors, such as patient fixation and the operator’s ability to consistently place the macular grid over the same points during each scan.”